The present invention relates to an anchor, and more particularly, to an anchor used chiefly for mooring large-sized structures floating on the sea, such as floating piers, buoys, floating breakwaters, offshore platforms, oil storage vessels, etc.
Floating offshore structures of such a large size are frequently held onto the sea bottom with anchors, which must possess a great holding power for retaining the floating structure against winds, waves and currents. The heavier, the anchor, the greater the holding power. However, anchors of increased weight are costly and difficult to handle. Further with elongated large offshore structures, it is also common practice to hold one end only of the structure with a single anchor in order to permit the structure to shift to a direction such that the external forces acting, for example, the force winds, waves and currents acting on the structure will always be minimized, even when the direction of the force changes. However, conventional anchors are adapted to afford a great holding power by digging into sludge, mud, sand and like deposits (hereinafter referred to collectively as "sand") on the bottom of the sea only when they are pulled in a specific direction, so that, if the conventional anchors are pulled in a different direction, the anchor becomes dislodged from the sand, then shifts in direction while moving toward the direction of the pull and thereafter lodges in the sand. Thus every time the floating structure shifts in direction, the conventional anchor also shifts, failing to hold the structure in a specified location. It is therefore desirable to provide an anchor having a great holding power against a pull or drag in every direction.